The present invention is directed towards an automated tool and appertaining method to assist in designing and manufacturing the 3D shape of an in-the-ear hearing aid shell.
The development of 3D modeling technologies for hearing aid design and manufacturing has created a new impetus in hearing instrument technology. In these developments within the hearing aid industry, emphasis has been directed at adapting manually intensive processes into software in order to reduce inherently laborious and uncomfortably repetitive manual processes. To date, there has been little adaptation of analytical and decision-making technologies to facilitate robust automation of hearing instrument manufacturing. The analytical complexity resulting from significant divergence in ear canal shape distribution makes the accurate replication of hearing instrument modeling a daunting task.
In order to accommodate the variance in ear canal shape, physical casts of the ear and ear canal (“impressions”) are created in order to facilitate the design for completely-in-the-canal (CIC) hearing aids, which are a type of in-the-ear (ITE) devices (this refers to a class of hearing aid instruments, usually the full concha type) that, as the name suggests fit completely or nearly completely within the ear canal.
For the sake of clarity, the following definitions and explanations are provided. An “impression” refers to mold material that is initially inserted and then extracted from a patient's ear. This represents a physical replicate of the patient ear canal characteristics. The term “impression” can also refer to the point set data obtained from a 3D scanner of a mold.
A “canal” is a continuous section of the impression extending from the aperture to the canal tip, where the “aperture” is the largest contour located at the entrance to or outermost portion of the canal, and the “canal tip” is the highest or innermost point on the canal. The “second bend” is one of two curvatures points that occur between the aperture and the canal tip. It may or may not be distinct for some ear canals, and is a function of ear canal curvature. The “bony part” refers to the end of the canal tip, which essentially extends towards the inner part of the ear where bone is present.
Currently, the hearing aid shell detailing is a manual process. Detailing is a term that refers to the process of reducing an impression mold either elctronically or manually to a prescribed device size. This manual state of the art technique requires the technician to make the following decisions: a) manually determine the direction of the bony part of the ear to ensure optimal performance of a wireless system (i.e., optimizing a binaural pair of hearing devices for wireless communication between them). This involves using a graduated angular measurement device, which is a device that has a range of angles corresponding to an optimal value and a range of allowable angles; b) determine the location on the impression to initiate a final cut for the shell; and c) determine the criterion to use to determine whether a fixed or floating microphone assembly configuration shall be used. A complex manual detailing procedure with intermittent manual angular measurements has been used to facilitate this process, however, there is currently no present mechanism to achieve automated feature-based and rule-based detailing of the hearing aid shell.
The manual steps of detailing the shell and making correct measurements and cuts are proned to error and are time consuming. What is needed in the industry is a procedure that permits an automated feature-based and rule-based 3D detailing of a hearing aid device for an ear canal having a particular shape.